JPH0476410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention includes a measuring tube made of an electrically insulating material, a magnetic device, and two measuring electrodes. The magnet arrangement furthermore has an electromagnetic coil arrangement and a yoke for the return path, and two measuring electrodes are respectively arranged between each pole piece. Regarding electromagnetic flowmeters.

BACKGROUND OF THE INVENTION In a known flowmeter of this type (European Patent Application Publication No. 80535), flanges are provided on both end faces of a measuring tube made of ceramic material. Each pole piece has an electromagnetic coil adjacent to it.
The axis of the electromagnetic coil is radial and perpendicular to the axis of the measuring electrode. A steel casing with a radially biased measuring tube accommodated in a bore is used in magnetic devices as a return path.

In such an arrangement, the magnet device projects significantly in the radial direction beyond the flange of the measuring tube. Therefore, the outer circumference becomes relatively large.
Furthermore, the electromagnetic coil often becomes an impediment to the threading of the tightening bolt. This tightening bolt is 2
Used to securely fasten the flowmeter between each flange of two connecting pipe sections. The position and number of such tightening bolts are determined by the respective standard.

Problem to be Solved by the Invention The object of the invention is to provide an electromagnetic flow of the type mentioned at the outset which has smaller dimensions than in the prior case under otherwise identical conditions and which hardly interferes with the tightening of the clamping bolt. The objective is to provide a measurement system.

Structure of the Invention This problem is solved according to the present invention, in which the electromagnetic coil device is constituted by an electromagnetic coil winding each magnetic pole piece, and the electromagnetic coil is arranged coaxially with the measuring tube, and each The pole pieces are arranged in such a way that they are connected to the yoke via a radial web element on each mutually opposite end side of the electromagnetic coil.

Particularly advantageously, the yoke has a cylindrical inner circumference, and the radial web members are each segmented.
It is constituted by a ring consisting of at least two circumferential parts. This radial web ring is segmented so that it can be easily attached to the measuring tube. The ring can then be held fixed by the cylindrical inner circumference of the yoke in such a way that the magnetic circuit is also closed. That is, by making the yoke and the radial web member ring-shaped, a large circumferential area is obtained, which allows them to be held fixed so that the magnetic reluctance in the return path is low.

Preferably, at least one of each radial web ring portion is formed integrally with the pole piece. In this way, the number of parts can be correspondingly reduced and assembly can be simplified.

It is particularly advantageous if the radial web ring is divided by a radial plane that approximately bisects the pole piece. In this plane, no or only a few magnetic field lines occur that need to be guided through this dividing seam.

It is advantageous if the yoke is formed by a cylindrical sleeve. The radial dimension of this sleeve has a small extent, so that the outer circumferential dimension can be reduced.

If a measuring tube with an end flange is used, the radial web ring can be constructed in such a way that it has an outer diameter equal to or larger than the flange diameter. The yoke does not interfere with the installation of the tightening bolts, so
The size of the upward dimension can be limited. In this way, a yoke with a cylindrical inner circumference can be fitted coaxially into the measuring tube and other magnetic devices without difficulty. If both diameters are made equal, the yoke or cylinder sleeve can also be used to apply a radial biasing force to the flange of the measuring tube.

It is particularly advantageous if the radial web element has a cross section that increases radially outwardly. In this way, a large circumferential area is obtained and the losses during the transition of the magnetic field lines from the radial web member to the yoke are correspondingly reduced.

The radial web member may also have an axially extending extension on its outer periphery. In this way, magnetic material can be saved. Additionally, a space is provided between the radial web member and the flange which can be used to guide the lead wires.

In this advantageous embodiment, the leads of the measuring electrodes are guided outside the measuring tube in the space formed between the respective pole pieces up to the radial web element and are led out from there. ing. that time,
Only one exit hole is required in the area of the radial web member, which does not adversely affect the magnet arrangement. In any case, if an annular space is provided along the radial web element, the lead wire can be guided in a very simple manner.

Furthermore, at least one pole piece can have a circumferential groove for receiving the lead wire of the measuring electrode. This lead wire can then be guided towards the counter electrode and then both lead wires can be laid together.

It is particularly advantageous to provide a cylindrical shield made of electrically conductive material on the inner periphery of the electromagnetic coil. This shield is
Prevents capacitive coupling between the electrode and electromagnetic coil,
As a result, the extracted signal is not adversely affected by capacitive effects. Furthermore, a shield plate can be used to keep the pole pieces in place, at least during assembly.

Embodiment The measuring tube 1 of FIGS. 1 and 2 has an axial flow path 2, and one flange 3 or 4 is provided at each end of the measuring tube 1. The measuring tube 1 shown in FIGS.
The measuring tube 1 is made of electrically insulating plastic or preferably ceramic. Therefore,
An annular groove 5 is formed between both flanges.

Two pole pieces 6 , 7 are arranged on mutually opposite sides in the annular groove 5 , and these two pole pieces 6 , 7 rest against the measuring tube 1 . The magnetic pole piece 6 is
A radial web ring 8 follows, and the pole piece 7 follows a radial web ring 9. The two radial web rings 8, 9 are made of magnetically conductive material and are divided by a radial plane that passes through the axis of the measuring tube 1 and is perpendicular to the plane of the drawing. An electromagnetic coil 10 is wound around both magnetic pole pieces 6 and 7, and the axis of the electromagnetic coil 10 is aligned with the measuring tube 1.
coincides with the axis of A shield 11 made of a conductive material such as aluminum is provided between the electromagnetic coil 10 and the measuring tube 1. A cylindrical sleeve is used as yoke 12 for the return path, the cylindrical inner circumference of which is equal to the outer circumference of the flanges 3, 4 and the outer circumference of the radial web rings 8, 9.

The two measuring electrodes 13, 14 are arranged on mutually opposite sides of the inner wall of the measuring tube 1. The axes of the measuring electrodes 13, 14 are perpendicular to the plane of symmetry of the pole pieces 6, 7.

When assembling this flowmeter, the pole piece 6 with radial web ring 8 and the pole piece 7 with radial web ring 9 can be assembled directly into position and temporarily protected by the shield 11. It can be held fixedly. Then the electromagnetic coil 10 is wound and finally the sleeve-like yoke 12 can be coaxially fitted onto the electromagnetic coil 10.

In operation, the electromagnetic coil 10, which is concentric with respect to the measuring tube 1, generates a magnetic field that penetrates the flow channel 2 in a radial direction. This is because the pole pieces 6, 7 are connected to a sleeve-shaped return path yoke 12 via radial web rings 8, 9 on mutually opposite end sides of the electromagnetic coil 10.

The flow meter is attached between two connecting pipe sections 17 and 18 via packings 15 and 16. Each tightening bolt 19 is disposed on a circumference centered on the axis of the measuring tube 1, and passes through each flange of the connecting tube portions 17, 18. The outer diameter of the sleeve-shaped yoke 12 lies entirely radially inside each tightening bolt 19.

In the case of the embodiments shown in FIGS. 3 and 4, the embodiments shown in FIGS.
The parts corresponding to the case in the figure are numbered 20 higher than in the case of FIGS. 1 and 2. In the embodiment shown in FIGS. 3 and 4, the radial web ring 28 is divided into two parts 28a, 28b along the dividing seam F, and the radial web ring 29 is disposed along the dividing seam F. It can be seen that it is divided into two parts 29a and 29b along the line.
In this case, the portion 28a is formed integrally with the magnetic pole piece 26, and the portion 29a is formed integrally with the magnetic pole piece 27. Each radial web ring portion has an extension 35 coaxial to the radial flange. As a result, a large abutment surface is obtained on the cylindrical sleeve used as yoke 32. In this case, the outer diameter of the radial web rings 28, 29 is greater than the outer diameter of the flanges 23, 24. Each flange is surrounded by a tightening ring 36;
The clamping ring 36 applies a radial biasing force and is, for example, fitted. Both tightening rings 36
are interconnected by a protective sleeve 37.

The measurement electrode 33 is provided with a lead wire 38, and the measurement electrode 34 is provided with a lead wire 39. The lead wire 38 is guided through a circumferential groove 40 provided inside the pole piece 27 . The two lead wires are then led through the space 41 between the two pole pieces outside the measuring tube 21. Additionally, both leads are connected to a radial web ring 28.
and the flange 24 , and through an outlet hole 43 provided in the ring 28 , the sleeve-like yoke 32 and the protective sleeve 37 . A lead wire 44 for the electromagnetic coil 30 is also taken out through the same exit hole.

Assembly or installation takes place in this embodiment in the same manner as in the embodiments of FIGS. 1 and 2.

In the case of the variant embodiment of FIG. 5, parts corresponding to those of the previously described embodiment are numbered 50 higher than in FIGS. 1 and 2; The numbers are 30 larger than in the figure. The substantial difference is that the radial web ring 58 is divided into two parts 58a, 58b, with the seam F of the parts 58a, 58b passing through the midplane of the pole piece 56. In particular, this pole face 56 is thus also formed from two parts 56a, 56b, which are respectively connected to respective halves 58a, 58b of the radial web ring 58. Correspondingly, the radial web ring 5
9, the seam F is also in the same plane as in the case of the radial web ring 58, and the two halves 59a, 5
9b.

Effects of the Invention In the configuration of the electromagnetic flowmeter of the present invention, one electromagnetic coil can be disposed coaxially with respect to the measurement tube. Therefore, a sufficient number of windings can be accommodated with relatively little expansion in the radial direction. Due to the special combination of pole piece and yoke,
Even though the electromagnetic coil is wound tangentially, it is possible to ensure that the effective magnetic field penetrates the measuring tube radially. Since the radial extent is relatively small, the path of the magnetic path can also be relatively short. Therefore, the drop in magnetomotive force can be made relatively small, and the temperature dependence of the magnetic permeability of iron can be made relatively small. Since the flowmeter has a generally small radial dimension, tightening bolts can be provided at arbitrary positions around the flowmeter. In many cases, the diameter of the flange of the flow meter of the invention need not be larger, or only slightly larger, than the diameter of flanges normally used for measuring tubes. In particular, the magnet arrangement and the entire flow meter can be arranged completely radially inside the clamping bolt.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the electrode flowmeter of the present invention, and FIG. 2 is a dashed-dotted line AA in FIG.
FIG. 3 is a view showing the inside of the yoke in the direction of the arrow when cut along the direction of the arrow, and shows a measurement tube of another embodiment of the present invention.
FIG. 4 is a partially cross-sectional perspective view of the pole piece, radial web-ring, and FIG. 4 is a partially cross-sectional view of the electrode flowmeter of the FIG. 3 embodiment after all parts have been assembled. A perspective view, FIG. 5, shows another modified embodiment of the embodiment of FIG. 3. 1, 21, 51...Measuring tube, 2, 22, 52...
...Flow path, 3, 4, 23, 24, 53, 54...
End flange, 5... Annular groove, 6, 7, 26, 2
7, 56, 57...Magnetic pole piece, 8, 9, 28, 2
9, 58, 59... radial web member, 10,
30... Electromagnetic coil, 11, 31... Shielding body,
12, 32... York, 13, 14, 33, 34
...Measurement electromagnetic, 15,16...Patsukin, 17,
18... Connection pipe section, 19... Tightening bolt, 36
... Tightening ring, 37 ... Protective sleeve, 3
8, 39, 44...Lead wire, 43...Exit hole.

Claims (1)

[Claims] 1. Comprising a measuring tube made of electrically insulating material, a magnetic device, and two measuring electrodes, the magnetic device having one magnetic pole piece on each mutually opposing side of the measuring tube. The magnet device further includes an electromagnetic coil device and a yoke for the return magnetic path, and the two measuring electromagnetic poles are arranged between each magnetic piece. , each magnetic pole piece 6, 7; 26, 27; 56,
The electromagnetic coil is composed of an electromagnetic coil 10 and 30 which are wound around a measuring tube 1;
21; 51, each said pole piece being arranged coaxially with a radial web member 8, 9; 28, 29; 58,
An electromagnetic flowmeter characterized in that it is coupled to a yoke 12; 32 via a yoke 59. 2. The yoke 12; 32 has a cylindrical inner circumference, and the radial web members are each segmented,
2. An electromagnetic flowmeter according to claim 1, wherein the flowmeter is constituted by a ring (8, 9; 28, 29; 58, 59) consisting of at least two circumferential parts. 3 Each radial web ring portion 28a, 29
The electromagnetic flowmeter according to claim 2, wherein at least one of a; 58a; 58b, 59a, 59b is integrally formed with the magnetic pole pieces 26, 27; 56, 57. 4. An electromagnetic flowmeter according to claim 1, wherein the radial web rings 58, 59 are divided by a radial plane that approximately bisects the pole pieces 56, 57. 5. The electromagnetic flowmeter according to claim 1, wherein the yoke 12; 32 is formed of a cylindrical sleeve. 6. When using a measuring tube 1; 21 with end flanges 3, 4; 23, 24, the radial web rings 8, 9; 28, 29 have the same outer diameter as the flange diameter or The electromagnetic flowmeter according to any one of claims 2 to 5, having an outer diameter larger than the flange diameter. 7. Electromagnetic flowmeter according to claim 1, wherein the radial web members 8, 9 have a cross section that increases radially outward. 8. The electromagnetic flowmeter according to claim 1, wherein the radial web members 28, 29 have an extension 35 extending in the axial direction on the outer periphery. 9 The lead wires 38 and 39 of the measurement electrode are connected to the measurement tube 2.
1 to the radial web member 28 in a space 41 formed between each pole piece 26, 27 on the outside of the pole piece 28, and extending outwardly from there. The electromagnetic flowmeter described in item 1 up to item 8. 10. An electromagnetic flowmeter according to claim 9, wherein at least one pole piece 27 has a circumferential groove 40 for receiving a lead wire 38 of a defined electrode. 11. The electromagnetic flowmeter according to claim 1, wherein a cylindrical shield 11; 31 made of a conductive material is provided on the inner periphery of the electromagnetic coil 10; 30.